1. Field of the Invention
This invention pertains, in general, to the field of hydraulic actuating systems and, in particular, to an arrangement whereby hydraulics are used to control the sequencing of and operation of mechanical actuating apparatus as applied to the opening, closing and latching of a large door.
2. Description of the Prior Art
Hydraulic actuating systems have, of course, been used in the past for purposes of opening and closing doors and the like. This includes sequencing of the operations involved whereby door unlocking apparatus is actuated followed by door opening and then locking of the door in the open position. Such sequencing also accomplishes a reverse procedure whereby the door is closed and then locked in a closed position.
In the past, such systems have involved complicated combinations of electrical systems, hydraulic systems, and mechanical systems. In general, complicated systems tend to be unreliable. Unreliability of such systems as applied to, for example, large cargo doors on airplanes cannot be tolerated and therefore require a backup system. Backup systems are problematic in themselves, in that, they too are often complicated and, therefore, unreliable. Moreover, backup systems are less frequently required to be operated as compared to the main system. Infrequent operation can also lead to system failure. Therefore, as applied to airplane cargo doors, a prime objective of any system is high or increased reliability and, accordingly, is an object of the present invention.
A simple and reliable backup system is yet another object of the present invention.
A further object of the present invention is to provide a mechanical arrangement which works in conjunction with a hydraulic system and which is simple but yet effective to securely latch the door in a closed position in order to prevent accidental or inadvertent opening thereof when the airplane is in flight.
An even further object of the present invention is to provide a combination hydraulic and mechanical arrangement whereby a cargo door which is both large and heavy may be securely locked in an open position in order to prevent accidental closing thereof.
The above-stated objects as well as other objects which although not specifically stated, but are intended to be included within the scope of the present invention, are accomplished by the present invention.